Apparatus for cooling continuous castings

ABSTRACT

A continuously cast strand as it leaves the casting mold is cooled by cooling elements comprising cooling plates having surfaces spaced from the strand by guide elements, preferably adjustable, which protrude from the surfaces of the plates to engage the surface of the strand and establish and maintain a gap between the strand surface and the plate surfaces to permit flow of coolant introduced into the gap through said plates.

United States Patent Meier et al.

APPARATUS FOR COOLING CONTINUOUS CASTINGS Walter Meier, Winterthur; Max Burkhardt, Zurich; Armin Thalmann, Uster, all

Inventors:

Appl. No.: 41,203

Foreign Application Priority Data [151 3,654,989 1451 Apr.11, 1972 Primary Examiner Frederick L. Matteson Assistant Examiner-W. C; Anderson Attorney-Sandoe, l-lopgood & Calimafde [57] ABSTRACT May 30, 1969 Switzerland ..8229/69 A continuously cast strand as it leaves the casting mold is cooled by cooling elements comprising cooling plates having US. Cl ..165/47, 165/ 120, 164/89, surfaces spaced from the strand by guide elements, preferably 164/283, 164/348 adjustable, which protrude from the surfaces of the plates to Int. Cl ..B22d 11/12 ng g the surf e of h s r nd and establi h and maintain a Field of Search ..l64/89, 283, 348; 165/ 120 g p between the stra d su and th plate surfaces to permit flow of coolant introduced into the gap through said plates.

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I N VEN'I ()RS WALTER MEIER MAX BURKHARDT BY ARMIN THALMANN I ATTORNEYS PATENTED PR 11 I972 3,654,989

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APPARATUS FOR COOLING CONTINUOUS CASTINGS This invention relates to apparatus for cooling continuously cast steel strands with cooling elements comprising cooling plates which are spaced from the strand and are adjustable to form a gap of the desired width between the strand surface and the surfaces of the plates through which coolants are introduced through apertures in the plates.

US. Pat. No. 3,399,716 discloses the cooling of a strand by cooling plates which form a gap between the strand surface and the plates, said plates having provision for introducing coolants into said gap. However, when casting strands such as slabs of large cross-section, it is difficult to maintain a gap of constant width between the strand surface and the cooling plates, as is necessary for uniform cooling. Strand supporting rolls located in spaces between successive cooling plates do not reliably maintain a gap of the desired constant width in the regions close to the mold, because the relatively thin solidified wall of the strand tends to bulge between the rolls.

Experience has shown also that the cooling plates are subjected to excessive wear, not only due to friction caused by bulges in the wall of the casting, but also due to distortion of the plate itself. The combination of these factors adds to the difficulty of maintaining the desired gap width. Moreover, the wear on the cooling plates and the need for frequent replacement adds to the cost of operation.

It is an object of the present invention to provide a cooling plate which ensures the maintenance of the desired gap width, reduces wear, improves the support of the solidified wall of the casting and increases the uniformity of the cooling effect.

According to the present invention this is achieved by the provision of guide elements protruding from the surface of the cooling plate facing the casting which engage the surface of the casting and determine the width of the cooling gap.

In order to provide a maximum number of guide elements evenly distributed across the width of the casting, guide elements which are directly consecutive in strand travel direction are preferably offset transversely to each other.

To prevent scale from restricting the entry of coolant into the cooling gap, the coolant inlet openings may be located on the downstream side of the guide elements in strand travel direction.

It is advantageous to use set screws as guide elements for easy replacement and also for a quick adjustment of the cooling gap width.

If desired, the set screws which form the guide elements may be provided with means for admitting the coolant into the gap, which will also cool the screws.

To provide satisfactory support for the relatively thin solidified wall of the casting in high speed casting machines, and also to provide a uniform cooling effect, the guide elements may conveniently take the form of parallel strips protruding from the surface of the cooling plate and extending in strand travel direction. In this case, the total area of the guide elements is preferably substantially equal to the recessed areas of the plate lying between the guide elements.

According to yet another feature of the invention the cooling element may consist of a plurality of component plates which tend to prevent warping. This also simplifies manufacture of the plates and replacement of the component plates when necessary. Spaces may be provided between the component plates to allow for thermal expansion.

Preferred embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a section of part of a cooling element taken on the line 1-1 ofFIG. 1.

FIG. 2 is a front view of a cooling plate.

FIG. 3 is a section of part of a modified form of cooling element.

FIG. 4 is a front view of part of two cooling plates which are consecutive in strand travel direction, and

FIG. 5 is a section of a cooling element taken on the line 5- 5 in FIG. 4.

In FIG. 1 the surface 2 of a casting 3 is cooled and supported by a cooling element 1 which is only partly shown. For maintaining the width of the cooling gap 9 between the surface 2 of the casting and the opposed cooling surface of the plate 4, the latter is provided with guide elements which, in this embodiment, consist of set screws 6 having rounded ends 5 which facilitate the sliding of the casting on the guide elements.

For minimizing abrasive wear the ends 5 of the guide elements may have a wear-resistant coating, or the set screws 6 may be made of a nitride hardened chrome steel. Altematively, the ends 5 of the guide elements may be hardened by welding or spraying or may have hard metal tips. If a high thermal conductivity of the guide elements is required, a wear-resistant layer may be directly applied to a copper base.

The width of the cooling gap 9 is determined by adjustment of the set screws 6. It has been found that optimum cooling effect can be obtained when the cooling gap 9 is about 1 mm wide. A differentiated cooling effect, as for instance along the corners of a casting of rectangular cross-section can be obtained by making a suitably differentiated adjustment of the cooling gap width by means of set screws 6.

If the surface of the casting is curved the set screws 6 can be so adjusted that all guide elements engage and support the casting even if the plate 4 itself is not curved but flat.

For cooling of the surface 2 of the casting coolant is conducted into the gap through inlets 8. The inlet pressure of the coolant may be as high'as 2.5 atm. gauge. The cooling element 1 itself is cooled by water spray nozzles 7.

FIG. 2 shows a preferred arrangement of the guide elements on the plate 4. Arrow 20 indicates the direction of travel of the casting. The guide elements which are consecutively spaced in the direction of travel of the casting are offset transversely to each other by a distance 21. To prevent an overlap between the guide elements the transverse distance 21 must be at least equal to the diameter of the guide elements. By such an arrangement of the guide elements a uniform clearance gap 9 can be maintained across the width of the cooling element 1 while using only a minimum number of guide elements, thereby creating a uniform cooling effect. In the described arrangement the rows of guide elements for a slab of say 1,000 mm width are preferably spaced in casting travel direction at distances of about mm between rows, and the elements of each row are spaced transversely at distances of about mm between centers. The coolant inlets 8 are evenly distributed between the guide elements.

The guide elements which in this embodiment are formed by the ends of set screws 6 arranged in rows may be arranged on the plate 4 in different patterns if desired. Instead of set screws, guide elements may also be created in the shape of bosses or ribs by welding or spraying hard material onto the plate.

In FIG. 3 the guide element of a cooling element 38 is formed by the end 5 of set screw 31. A backing screw 37 in a bracket 36 supports the set screw 31 which is adjusted to the desired width 9 of the cooling gap. A coolant passage 32 is formed by a flattening 33 on the set screw 31 on the downstream side of the casting direction as indicated by arrow 20. The cooling element 38 itself is cooled by coolant flowing through a passage 35.

FIGS. 4 and 5 show two cooling elements 40 and 40' which are consecutive in the direction of travel of the casting. Guide elements in the form of strips having faces 41 extend parallel to the direction of travel of the casting. Between the strips 41 are grooves having recessed faces 42 which are set back from the faces 41 by the desired cooling gap width 9. Coolant inlets 43 open into said grooves. The cooling elements 40 and 40' are cooled by coolant supplied through tubes 48 and circulating through the passages 44. The total area of the surfaces 41 preferably equals the total area of the surfaces of the recessed faces 42 in each cooling element 40 or 40' and they are arranged so that the faces 41 and 42 of cooling element 40 are offset laterally from the corresponding faces of the cooling element 40 so that there is no overlap. A cooling plate for a steel slab of about 2,000 mm width may have guide elements having faces 41 of about 50 mm width. Alternatively the striplike guide elements 41 may extend for only part of the plate length and may be followed by a recessed face 42 on the same plate. This results in a checkerboard pattern of guide elements 41 on a plate.

The cooling elements 40 and 40 may consist of a plurality of plates of a width 46 which may roughly correspond to the length of the plates. In this case the component plates are spaced laterally by distances 47 to allow for thermal expansion.

We claim as our invention:

1. Apparatus for cooling continuously cast steel strands with cooling elements comprising cooling plates having surfaces conforming to and facing opposed strand surfaces, said plates being provided with apertures through which coolants are applied directly to said opposed surfaces of the casting, and guide elements carried by said plates and protruding from said cooling plate surfaces and engaging said opposed surfaces of ments which are spaced consecutively in the direction of travel of the casting are offset transversely to each other without overlapping.

3. Apparatus according to claim 1, in which the guide elements are set screws extending through the said cooling plates.

4. Apparatus according to claim 3, in which said set screws are provided with passages for admitting coolant into the cool- 5. A ;)paratus according to claim 4, in which the said coolant passages are located on the downstream side of the set screws in strand travel direction.

6. Apparatus according to claim 1, in which guide elements are in the form of strips having faces which extend parallel to the direction of travel of the strand, and in which said strips are separated by grooves having recessed faces set back from said strip faces by the desired cooling gap width.

7. Apparatus according to claim 6, in which the total area of the surfaces of said strips is approximately equal to the total area of said recessed faces.

8. Apparatus according to claim 1, in which said cooling elements comprise a plurality of component cooling plates.

9. Apparatus according to claim 8, in which the said component cooling plates are spaced laterally. 

1. Apparatus for cooling continuously cast steel strands with cooling elements comprising cooling plates having surfaces conforming to and facing opposed strand surfaces, said plates being provided with apertures through which coolants are applied directly to said opposed surfaces of the casting, and guide elements carried by said plates and protruding from said cooling plate surfaces and engaging said opposed surfaces of the casting to maintain a cooling gap between said cooling plate surfaces and said opposed surfaces of the casting through which said coolants may flow.
 2. Apparatus according to claim 1, in which the guide elements which are spaced consecutively in the direction of travel of the casting are offset transversely to each other without overlapping.
 3. Apparatus according to claim 1, in which the guide elements are set screws extending through the said cooling plates.
 4. Apparatus according to claim 3, in which said set screws are provided with passages for admitting coolant into the cooling gap.
 5. Apparatus according to claim 4, in which the said coolant passages are located on the downstream side of the set screws in strand travel direction.
 6. Apparatus according to claim 1, in which guide elements are in the form of strips having faces which extend parallel to the direction of travel of the strand, and in which said strips are separated by grooves having recessed faces set back from said strip faces by the desired cooling gap width.
 7. Apparatus according to claim 6, in which the total area of the surfaces of said strips is approximately equal to the total area of said recessed faces.
 8. Apparatus according to claim 1, in which said cooling elements comprise a plurality of component cooling plates.
 9. Apparatus according to claim 8, in which the said component cooling plates are spaced laterally. 